Two Cadmium-Cluster-Based Metal–Organic Frameworks with Mixed Ligands of 1,2,3-Benzenetriazole (HBTA) and 1,4-Benzenedicarboxylic acid (H₂BDC)

Two cadmium­(II) metal–organic frameworks based on two mixed ligands of HBTA and H₂BDC, [Cd₅(BTA)₆(BDC)₂(DMF)₄(H₂O)₂]_n·n(2DMF·H₂O) (1) and [Cd₇(BTA)₂(BDC)₆(DMF)₈]_n·2nDMF (2) (HBTA = 1,2,3-benzenetriazole; H₂BDC = 1,4-benzenedicarboxylic acid), have been prepared through methods of liquid to liquid diffusion and solvothermal reaction, respectively. The results of single-crystal X-ray diffraction analyses indicate that both MOFs are constructed from cadmium clusters. In 1, six BTA^– anions connect five Cd­(II) ions to generate a tetrahedral Cd₅ cluster, which further links with four equivalent Cd₅ clusters through four BDC^2– bridges, forming a (4,4)-connected two–dimensional (2D) layer structure. In 2, each BTA^– anion connects three Cd­(II) ions to generate a triangular Cd₃ cluster, which further links with four Cd₃ clusters and two 3-connected BDC^2– anions, forming a (3,6)-connected three-dimensional (3D) framework. The results of photoluminescent measurements illustrate that in the solid state, both 1 and 2 can emit fluorescence at 465 and 450 nm, respectively.